SINCE its launch in 1975 the BMW 3 Series has become one of the best selling cars of all time.

Six incarnations of the iconic model have seen more than 15 million compact executive motors roll off the production line.

So does the latest G20 version represent a magnificent seven or is there any hint of weakness?

It is certainly the biggest 3 Series yet with the increased dimensions allowing major improvements to passenger space and refinement.

Life in the cabin - particularly in the back where the extra leg and headroom is particularly welcome - is vastly improved thanks to a stretched wheelbase with exterior noise irritants kept firmly at bay providing a relaxed atmosphere on long journeys.

Three adults can be accommodated easily at the back although the transmission tunnel does use up some of the middle passenger's legroom.

Entering and exiting the car is simpler for the rear passengers now as the door aperture height has also been increased.

Up front, on the M Sport model, figure-hugging Vernasca leather heated sports seats are the order of the day with powered adjustment allowing the driver to attain the perfect position behind the wheel.

There are plenty of cubby holes and drinks holders while the boot can swallow 480 litres of luggage or shopping.

The interior is a high-quality affair boasting a ton of technology that is integrated seamlessly into the dashboard design featuring a 10-inch colour touchscreen and BMW's new Intelligent Personal Assistant allowing you to communicate with the car to alter the temperature, control the stereo system or talk to the sat nav - although it can do nothing about you shouting at the traffic.

For dinosaurs like me the iDrive controller is still there allowing traditional buttons to be pressed and a rotary dial to be turned or you can use the touchscreen.

The M Sport model also gets BMW's new Live Cockpit Professional which includes a 12.3-inch digital dashboard display and the ability to customise the information shown to your heart's content.

Other goodies include digital radio as well as BMW's Connected+ giving access to Apps and online services while Apple CarPlay is standard across the range. There is also Bluetooth for calls and music streaming along with USB charging points.

Options adding to the cost of the £36,800 model I drove include a £1,800 technology package featuring a natty head-up colour display, enhanced Bluetooth with wireless charging, gesture control and a WiFi hotspot preparation.

The exterior of the G20 is more evolution than revolution so it is obviously a member of the BMW family with trademark LED headlights and the kidney grilles. It looks sleek with snazzy alloy wheels and a hunkered down profile that gives a clue to the superb handling and smooth-as-silk ride.

This is a saloon that is a pleasure to drive as it demonstrates the balance of a ballerina with informative steering pointing the way for a lithe 2.0-litre diesel engine that is aided and abetted by multi-stage turbocharging and a top-notch eight-speed automatic transmission.

The use of lightweight materials helps fuel efficiency with this oil burner achieving a shade over 55mpg under the new WLTP testing regime while emissions are 115g/km.

The 55kg shaved off the weight compared to its predecessor also allows top notch performance with the rear-wheel driven model sprinting to 62mph from a standing start in 6.8 seconds on its way to a top speed of 149mph.